Standard of care for surgical resection of rectal cancer is the performance of low anterior resection (LAR). After removal of the cancerous segment, a surgical stapler is used to restore continuity by creating an anastomosis between the resulting ends of disjointed bowel. Anastomotic leak is one of the most dreaded complications of colorectal surgery due to the morbidity and mortality caused by fecal contamination of the abdominal cavity. Anastomotic leak, after LAR for rectal cancer, has been reported to occur in as many as 14% of patients; three times more frequently than with other bowel resections. The sequela of anastomotic leak can include local abscess formation, debilitating pain, dysfunctional defecation, overwhelming bacterial sepsis, and death. The consequences are so severe that surgeons subjectively opt to divert the fecal stream away from the healing anastomosis to an ostomy; many months later the patient is then subject to an additional operation to restore normal defecation. While creation of a diverting ostomy can lessen the impact of anastomotic leak, it does not prevent the leak, and poses a high risk for additional complications while significantly compromising the lifestyle of the recovering patient. There is neither a clinically practical method available for predicting which patients will experience an anastomotic leak, nor an objective set of criteria by which a surgeon can select those patients that would benefit from an ostomy. The long term goal of the proposed research is to reduce the rate of anastomotic leak and unnecessary ostomy diversion through the creation of an objective, repeatable means by which to screen patients intra-operatively. Patients at low risk will avoid an unnecessary ostomy. Patients at high risk of leak, despite efforts to improve tissue viability, would likely be better served by a permanent ostomy instead of a failed, painful attempt at a restorative procedure. Postulated mechanisms for the increased incidence of leak after resection of rectal cancer can each contribute to inadequate oxygen delivery to the healing anastomosis; each of which are present at the time of surgery. The Stapled Anastomosis Viability Evaluation (SAVE) System integrates into the surgical workflow by replacing the anvil of commercially available, circular staplers with a sensing anvil. The SAVE Anvil uses an array of multi-modality sensors to enable the surgeon to perform the procedure in a standardized manner while assessing the viability of the anastomosis at the staple line throughout its formation. Sensor data is transmitted to a base station where actionable information is displayed to the surgical team. Phase I demonstrated the feasibility of measuring interstitial oxygenation levels at the anastomotic site using oxygen dependent quenching of phosphorescence via a locally injected phosphor. Initial toxicity studies of the probe indicate non-toxicity at dose-response levels. Phase II of this study will establish the relationship between interstitial oxygen level and integrity of the anastomosis through survival studies in animal models. Concurrently the candidate phosphor with undergo requisite screening, and pharmacokinetic evaluation in preparation for pre-IND discussion.